Gene Linked to Obesity Has Role in Different Types of Human Behavior

11/19/2013

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Researchers discovered that a gene with a known role in obesity also plays
an unexpected role in human behavior. The gene,
called SH2B1, is a key regulator of leptin sensitivity
in mice; leptin is a hormone that suppresses appetite.
Previous research showed that mice lacking the SH2B1
gene have impaired leptin and insulin signaling,
making them severely obese and insulin resistant. To
investigate the role of SH2B1 in human metabolism,
scientists examined whether obese people had
mutations in their SH2B1 gene. They studied people
with severe early‑onset obesity (developed before
age 10) who also had higher than expected levels of
insulin resistance for their weight. They identiied
four different types of mutations in the SH2B1 gene
that were not found in people who are normal weight.
The mutations were inherited from their overweight
or obese parents. The people with these mutations had
excessive appetites and at adulthood were a shorter
height than average. A surprising inding was that
they also had behavioral abnormalities, as reported
by their families and health care providers. These
abnormalities included delayed speech and language
development, aggressive behavior, and a tendency
toward social isolation. Further experiments showed
that some of the identiied mutations impaired leptin
signaling while others did not, suggesting that the
SH2B1 protein may be exerting some of its effects
through cellular pathways that are independent of
leptin. This research sheds new light on the human
SH2B1 gene and suggests that it not only plays a role
in obesity, but may also be an important factor in
controlling certain types of human behavior.